Ultra-fine particles or nanoparticle (particles having an average diameter of 200 nanometers or less) are believed to be useful in the fabrication of micro-electronic devices. Alivisatos et al., in U.S. Pat. No. 5,262,357, describe a method for making semi-conductor nanoparticles from metal precursors. Alivisatos et al. describe using these semi-conductor nanoparticles to make continuous semi-conductor films. Because the semi-conductor nanoparticles exhibit significantly lower melting temperature than bulk materials, a layer of the semi-conductor nanoparticle can be deposited on a substrate and annealed at relatively low temperatures, whereby the nanoparticles melt to form a continuous film.
One of the goals for nano-technology is to develop techniques and materials that will allow for the fabrication of micro-electronic devices on a variety of substrates using selective deposition, printing and/or imaging technologies. These selective deposition, printing and/or imaging technologies may utilize nanoparticle, or inks comprising nanoparticles, that can be used to fabricate micro-electronic devices at low temperatures and with high throughput.
To achieve the afore mentioned goal, it is necessary to develop new methods for making nanoparticles that can be used to fabricate continuous or patterned insulator layers, semi-conductor layers and conductive layers. To date, there has been limited ways to produce or make suitable metal nanoparticles having average particle sizes of 100 nanometers or less in high yield and with particle distribution size, which are suitable for inks to print micro-electronic devices and/or portions thereof. Previously disclosed methods for the synthesis of nanoparticles tend to be irreproducible, have low yields, produce particles with wide particles size distributions, produce particles with limited stability, produce particles which are insoluble in a suitable ink solvent or a combination thereof. Accordingly, there is a need for new methods of making metal nanoparticles for the fabrication of micro-electronic devices.